Food Processing Application Potential of Lactiplantibacillus plantarum and Bacillus subtilis Isolated from Fermented Food: Screening for Virulence Factors

Abstract

The identity and safety of two strains of Lactiplantibacillus plantarum and two strains of Bacillus subtilis, isolated from fermenting sweet potato broth and fermenting African yam beans seeds respectively, were evaluated using 16S rRNA gene sequences. The strains applicability for food fermentation were also practically determined.  The sequence analysis confirmed the two strains of Lactiplantibacillus plantarum (Lactiplantibacillus plantarum B1 and Lactiplantibacillus plantarum B4) with > 99 % similarities with related Lactiplantibacillus plantarum. The two studied strains of Bacillus subtilis (Bacillus subtilis FSB1 and Bacillus subtilis FSB2) had > 99 % relatedness in alignment with close Bacillus subtilis strains. Phylogenetic analysis based on 16S rRNA gene sequence was performed and phylogenetic trees were subsequently constructed to confirm taxonomic placement. The studied Bacillus subtilis FSB1 and Bacillus subtilis FSB2 strains fermented inoculated African yam bean seeds into food seasoning within 48 h of fermentation. Also, both the single Lactiplantibacillus plantarum B1 and Lactiplantibacillus plantarum B4 strains, and the combined starters produced fermented products with the relevant yoghurt flavour within 24 h of milk fermentation. Virulence profiling and vanA antibiotic resistance genes evaluation results suggested the absence of the studied gelE, hyl, sprE, asa1, cylA, esp virulence genes and vancomycin A resistance gene. This study demonstrated the safety and potential for application of the Lactiplantibacillus plantarum and Bacillus subtilis strains in food processing.